Are nest boxes really all they’re cracked up to be? Often touted as the key to the survival of hollow-dependent species, nest boxes have been the focus of recent analysis by WPSQ to determine just how important their role really is.
Since 2011, Wildlife Queensland’s Queensland Glider Network has been conducting biannual nest box monitoring in the Flinders Karawatha Corridor in southern Brisbane. However, recent analysis of the data collected over this period suggests the presence of some potentially worrying trends.
As indicated in Figure 1, nest box usage by gliders has dropped by almost 10 percent as part of a clear decline over the past two to three years. This is a particularly troubling statistic given that nest boxes were installed in areas assessed and identified as lacking sufficient numbers of natural tree hollows. As a result, one is forced to wonder why gliders aren’t making use of nest boxes in these areas.
Gliders may be absent from nest boxes due to fierce competition for hollows from a number of mammal and bird species reliant on them for breeding and denning purposes. This can be the case particularly in nest boxes with larger entrance holes, as they provide access for larger species, such as possums, which have no problem evicting gliders. It was noted that the percentages of boxes being utilised by both possums and native bees have increased over the same time period in which glider use declined, further indicating that competition may be a key factor in the decline.
So given the decline in their usage by gliders, are nest boxes as important for conservation of these species as they are claimed to be? Yes, Wildlife Queensland believes they are crucial. As tree hollows have been identified as a major limiting resource for gliders who rely on them for a wide range of life functions including denning, nesting and refuge from predators, the importance of nest boxes and increasing glider usage (Ball et al. 2011; Harper et al. 2005) is highlighted. With this problem being exacerbated by inter-specific competition, the importance is made even greater.
So the next, and harder, question is how can we increase glider nest box usage? Wildlife Queensland is beginning to understand the myriad factors which have the potential to impact a glider’s decision to use a specific box. Continued research and monitoring of installed nest boxes will be critical for better understanding of usage preferences, and allow management plans to be adapted accordingly.
One thing that is already clear, however, is the need to exclude competing species as much as possible by increasing the number of glider-specific nest boxes available. It is hoped that the installation of glider-specific boxes in the Flinders Karawatha Corridor will give local glider populations a greater chance of survival and allow us to live alongside these native animals for many more years to come.
Cameron Jones, University of Queensland placement student